Equalized rear suspension for multi-use vehicle

ABSTRACT

An equalized suspension system for a vehicle includes a first trailing arm, a second trailing arm, first and second wheels, and a cushion. The first trailing arm has a lower end pivotally secured to the first wheel, and an upper end pivotally secured to the frame. The second trailing arm has a lower end pivotally secured to the second wheel, a free upper end, and an intermediate portion pivotally secured to the frame. The cushion extends between the lower end of the first trailing arm and the free, upper end of the second trailing arm and serves to transfer and equalize pressures between the first and second wheels. When the first wheel engages an obstacle and moves in a first direction, the cushion forces the second wheel, via the second trailing arm, in a second direction.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to vehicle suspensions and, moreparticularly, toward equalized suspension systems for vehicles.

[0003] 2. Description of Related Art

[0004] It is known to independently suspend wheels from a vehicle frame.An independently suspended wheel is able to move in one or moredirections without affecting the movement of any other wheels. It isdesirable to independently suspend wheels to improve the ride of thevehicle when traveling over a road or ground that may be uneven. Often,a track is used on each side of the vehicle.

[0005] It is also known to suspend beams from vehicles. In a typicalconfiguration, a beam is suspended on each side of a vehicle. Two ormore wheels are attached to the beam. Typically, the beams areinterconnected by one or more axles or other structures so that thebeams move together relative to the frame. These types of structures arenormally used in areas where the terrain is likely to be substantiallylevel.

[0006] Such structures are unsatisfactory for use in an off-roadsetting. Typically, a multi-use vehicle (MUV) is used in an area wherethere are substantial differences in terrain on both sides of thevehicle. In an MUV setting, an independent suspension would beparticularly desirable since the variations in the level of the groundcan be substantial.

[0007] It is also desirable for a vehicle to include a system for evenlydistributing, or equalizing, the force on the wheels on one side of avehicle. The use of such a suspension system to equalize the pressure onthe wheels allows for an improved load distribution. Either of thewheels can then provide a drive force. In addition, the equalized loadreduces the probability of one wheel slipping. This further reduces theneed for limited slip or locking differentials. In addition, thedistribution of the force reduces the probability of the vehiclebecoming stuck due to high loading on one wheel on terrain such as softsoil or snow.

[0008] None of the suspension systems known in the art and describedhereinbefore are acceptable for use on an MUV. Specifically, none of theknown systems provide an independent suspension for a vehicle whereinthe pressure on the wheels on either side of the vehicle is equalized,as may be desirable during operation of the vehicle over soft orslippery terrain. There further exists a need in the art for an MUVsuspension that equalizes pressures on wheels on each side of thevehicle.

SUMMARY OF THE INVENTION

[0009] The present invention includes a number of components. Thevehicle includes a frame having a first side and a second side. A firstsuspension system is disposed on the first side of the frame and asecond suspension system, which is substantially identical to the firstsuspension system but separate therefrom, is disposed on the second sideof the frame.

[0010] In further accordance with the present invention, each suspensionsystem is associated with first and second wheels and includes a firstand second trailing arms. Each trailing arm is attached to the frame andone of the wheels. A single cushion extends between the first and secondtrailing arms and serves to equalize pressures experienced by the firstand second wheels.

[0011] In further accordance with the present invention, a firsttrailing arm has a lower end pivotally secured adjacent the first wheeland an upper end pivotally secured to the frame. The second trailing armhas a lower end pivotally secured adjacent the second wheel, anintermediate portion pivotally secured to the wheel, and a free upperend. The cushion extends between the lower end of the first trailing armand the upper end of the second trailing arm.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] These and further features of the invention will be apparent withreference to the following description and drawings, wherein:

[0013]FIG. 1 is a schematic side view of a particular embodiment of asuspension system according to the present invention; and,

[0014]FIGS. 2 and 3 schematically illustrate the suspension system ofFIG. 1 while traversing an obstacle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a suspension system for amulti-use vehicle. Initially, it is noted that the drawings are not toscale, but will be more easily understood by a person of ordinary skillin the art than drawings from another perspective or drawings shown inproper proportion. It is further noted that the drawings do not show anyother structures attached to the vehicle, nor do they show anystructures necessary for the functioning of the vehicle that are notdirectly related to the suspension structure disclosed. Accordingly, thevehicle shown in the drawing figures may not be functional without theother parts, such as a drive train and the like. However, any drivetrain that may be used in connection with the present structure isrelatively conventional in nature. A person of ordinary skill in the artcan easily adapt a known MUV drive train for use in connection with thepresent vehicle. Further, as the drawings only depict the rear portionof the vehicle, the conventional front or steered wheels are not shownherein. Moreover, the depicted vehicle may be a trailer that is towedbehind another vehicle, the trailer being adapted, as describedhereinafter, for use in an off-road setting.

[0016]FIG. 1 illustrates a preferred embodiment of a suspension systemin accordance with the present invention. This suspension system isuseful when there is a desire for the wheels on one side of a vehicle tomove independently of those on the other side of the vehicle. FIG. 1illustrates the inventive suspension on a first side of the vehicle, itbeing noted that the suspension system on the second or opposite side ofthe vehicle is identical thereto. Accordingly, the vehicle may beconsidered to be symmetrical about a longitudinal centerline.

[0017] Moreover, the suspension system described hereinafter illustratesjust a portion of the vehicle, it being apparent that other portions ofthe vehicle may be conventional and within the knowledge of thoseskilled in the art. For example, the suspension system may be used on avehicle incorporating a pair of front wheels (not shown) that aresteered by the driver and, accordingly, the wheels associated with thesuspension system are referred to hereinafter as a first or mid wheeland a second or rear wheel. Further, at least one of the mid and rearwheels may be powered by drive means (not shown), which may beconventional in nature. Alternatively, the vehicle may be used as atrailer in which neither the mid wheels nor the rear wheels are powered,as mentioned hereinbefore.

[0018] The suspension system 202 includes a mid wheel 206 a and a rearwheel 206 b. The mid wheel 206 a is rotatably secured to a mid axle 208a while the rear wheel 206 b is rotatably secured to a rear axle 208 b.The mid and rear axles 208 a, 208 b do not extend across the width ofthe vehicle. Rather, separate mid and rear axles 208 a, 208 b areprovided for each suspension system (i.e., half axles). Accordingly, thesuspension system on the first side of the vehicle may be considered tobe independent or separate from the suspension system on the second sideof the vehicle.

[0019] A first or forward trailing arm 212 extends forwardly from themid wheel 206 a, and is pivotally secured to the frame 210. Morespecifically, a lower end 212 a of the forward trailing arm 212 ispivotally secured adjacent the mid wheel 206 a, while an upper end 212 bof the forward trailing arm 212 is pivotally secured to the frame 210.

[0020] Similarly, a second or rearward trailing arm 214 extendsforwardly from the rear wheel 206 b and is pivotally attached to theframe 210. More specifically, the rearward trailing arm 214 has a lowerend 214 a, an upper end 214 b, and an intermediate portion 214 c. Therearward trailing arm lower end 214 a is pivotally secured adjacent therear wheel 206 b, while the intermediate portion 214 c is pivotallysecured to the frame 210. Accordingly, the rearward trailing arm 214extends upwardly and forwardly from the frame 210 toward the upper end214 b thereof.

[0021] Preferably, the forward and rearward trailing arms 212, 214 aresecured around the mid and rear axles 208 a, 208 b, respectively.Alternatively, the forward and rearward trailing arms may be secured tosupport structures disposed adjacent the wheels, such as a short supportrail (not shown) associated with each wheel 206 a, 206 b.

[0022] As illustrated in FIG. 1, the rearward trailing arm 214 is longerthan the forward trailing arm 212. A cushion 218 extends between theupper end 214 b of the rearward trailing arm 214 and the lower end 212 aof the forward trailing arm 212. The cushion 218 serves to equalize thepressures on each of the wheels 206. In FIG. 1, the two trailing arms212, 214 are illustrated in a rest position in which they aresubstantially parallel to one another. Furthermore, in the illustratedand most preferred embodiment, the cushion 218, in its rest position, isperpendicular to both arms 212, 214.

[0023] The upper or free end 214 b of the rearward trailing arm 214extends upwardly past the frame 210 and, for ease of design, preferablyextends on the outside of the frame 210. The angle at which the cushion218 meets the arms 212, 214 depends upon the spacing between the wheels206 a, 206 b and the length of the arms 212, 214. It is desirable toadjust these features to accommodate the desired perpendicularorientation of the cushion 218, as this orientation provides thegreatest initial force between the wheels and, therefore, the bestresult. Finally, it is most desirable for the rear arm 214 to be twicethe length of the front arm 212. This provides for the attachment of therearward trailing arm 214 to the frame 210 at about the midpoint of therear trailing arm. The need for such an orientation will be betterunderstood after a description of the operation of the suspensionsystem.

[0024] When one of the wheels 206 a, 206 b encounters an obstacle 211,such as a log, the pressure on the wheels 206 a, 206 b tends to remainequalized. For example and with reference to FIG. 2, if the mid wheel206 a encounters an obstacle 211, the mid wheel 206 a will move upwardlyand the forward trailing arm 212 will rotate in a counter-clockwisedirection (D₁) as the mid wheel 206 a travels over the obstacle 211. Inthis regard it is noted that the movement of the mid wheel 206 a is notpurely vertical, but rather will trace an arc, the radius of which isdefined by the distance between the pivotal connections of the lower andupper ends 212 a, 212 b of the forward trailing arm 212.

[0025] The movement of the forward trailing arm 212 will tend tocompress the cushion 218, which will, in turn, affect the rear wheel 206b by urging or biasing the rearward trailing arm 214 in a clockwisedirection (D₂). This is accomplished through the lever action at theupper or free end 214 b of the rearward trailing arm 214 whereby therearward trailing arm 214 rotates or pivots about the pivotal connectionbetween the frame 210 and the rearward trailing arm intermediate portion214 c. If the rear wheel 206 b is on the ground surface 213 during theforegoing operation, the rear wheel 206 b is pressed against the groundsurface 213 by the application of pressure from the cushion 218 againstthe upper end 214 b of the rearward trailing arm 214. The rear wheelwill be urged to move in a clockwise direction (D₂) but, due to theengagement with the ground surface 213, will remain in the illustratedposition.

[0026] As will be appreciated by those skilled in the art, in theillustrated embodiment the force (F₁) experienced at the mid wheel 206 aagainst the obstacle 211 will be generally equal to the force (F₂)applied to the rear wheel 206 b against the ground surface 213. Further,the force (F₂) applied at the rear wheel 206 b can be adjusted relativeto the force (F₁) experienced at the mid wheel 206 a by adjusting thelength of the rearward trailing arm 214, the relative location along thelength of the rearward trailing arm of the pivotal connection with theframe 210, and the angular orientation of the cushion relative to thetrailing arms 212, 214. Accordingly, although it is preferred that theforces (F₁, F₂) be equalized, it is contemplated that relatively more orless force could be experienced at one of the mid and rear wheels, ifdesired.

[0027] This system therefore increases the pressure between the rearwheel 206 b and the mid wheel 206 a, by increasing the pressure on therear wheel to be substantially similar to that of the mid rear wheel. Asimilar action results for each deflection and return of a wheel 206 a,206 b to or from any specified location to which it may travel, such asmay occur when the rear wheel 206 b encounters an obstacle, as shown inFIG. 3. By the use of this system, the force on the two wheels 206 a,206 b on each side of a vehicle is equalized, creating the benefitsdescribed above.

[0028] It is noted that the use of such a system requires additionalmodifications to the standard configuration. Of particular note is theneed for the stop structures (not shown) that mount the trailing arms212, 214 to the frame 210. Such stop structures will define a maximumrange of movement of the trailing arms 212, 214, and hence the wheels206 a, 206 b.

[0029] In a standard suspension system used in a typical MUV, thecushions restrict the ability of any given wheel to deflect from itsrest position, because the cushion is typically attached to both theframe and the wheel area. However, in the present system, the cushion218 provides no such resistance to deflection. Instead, the cushion 218simply equalizes the force between the wheels 206 a, 206 b. Accordingly,one or more stops should be included on the frame 210 to prevent eitherarm 212, 214 from deflecting too greatly from its rest position, andthereby prevent other damage to the vehicle. For example, should atleast one of the mid and rear wheels 206 a, 206 b be a driven wheel,there will be a maximum range of motion that the drive axle cantraverse. The stop structures for the trailing arms 212, 214 will bepositioned to prevent the mid and/or rear wheels from moving outside ofthe associated drive axle's maximum range of motion.

[0030] Although the present invention has been described withparticularity herein, it is considered apparent that the presentinvention is capable of numerous modifications, improvements, andsubstitutions of parts and therefore is not limited to the particularpreferred embodiments described herein. Rather, the invention is only tobe defined by the claims appended hereto.

What is claimed is:
 1. A multi-use vehicle, comprising: a frame having afirst side and a second side; a first suspension system disposed on thefirst side of the frame; and, a second suspension system substantiallyseparate from the first suspension system and disposed on the secondside of the frame; wherein each of said first and second suspensionsystems suspends first and second wheels from said frame and includesfirst and second trailing arms, said first trailing arms are pivotallysecured to the frame and the first wheels while the second trailing armsare secured to the frame and the second wheels, and wherein a firstcushion extends between the first and second trailing arms of the firstsuspension system and a second cushion extends between the first andsecond trailing arms of the second suspension system, said first andsecond cushions serving to equalize pressures experienced at said firstand second wheels.
 2. The multi-use vehicle according to claim 1,wherein said first wheels are mid wheels and said second wheels are rearwheels of said vehicle, at least one of said mid and rear wheels beingdriven wheels.
 3. The multi-use vehicle according to claim 1, whereinsaid first trailing arm includes a lower end and an upper end, saidlower end being pivotally secured adjacent the first wheel and saidupper end being pivotally secured to the frame.
 4. The multi-use vehicleaccording to claim 3, wherein said second trailing arm includes a lowerend, an upper end, and an intermediate portion disposed between saidsecond trailing arm upper and lower ends, said second trailing arm lowerend being pivotally secured adjacent said second wheel and saidintermediate portion being pivotally secured to said frame.
 5. Themulti-use vehicle according to claim 4, wherein said cushion extendsbetween said lower end of said first trailing arm and said upper end ofsaid second trailing arm.
 6. The multi-use vehicle according to claim 5,wherein said first trailing arm has a first length and said secondtrailing arm has a second length, said second length being greater thansaid first length.
 7. The multi-use vehicle according to claim 6,wherein, when said first wheel engages an obstacle, said trailing armrotates in a first direction and said second trailing arm is forced in asecond, opposite direction.
 8. A suspension system for a vehicle,comprising: first and second wheels; a first trailing arm having a lowerend pivotally secured to the first wheel; a second trailing arm having alower end and a free upper end, said second trailing arm lower end beingpivotally secured to the second wheel; and, a cushion extending betweensaid first trailing arm lower end and said second trailing arm upperend, said cushion serving to transfer and equalize pressures experiencedby said first and second wheels.
 9. The suspension system according toclaim 8, wherein said first trailing arm has a first length and saidsecond trailing arm has a second length, said second length beinggreater than said first length.
 10. The suspension system according toclaim 9, wherein, when said first wheel engages an obstacle, said firsttrailing arm rotates in a first direction and said second trailing armis forced in a second, opposite direction.
 11. The suspension systemaccording to claim 9, wherein, when one of said first and second wheelsmoves in a first direction said other of said first and second wheelsmoves in a second direction.